The invention generally relates to electronic displays and more specifically to the positioning of synthetic runway symbology on an aircraft display.
Under instrument flight conditions (i.e., poor visibility), pilots rely on instruments to navigate an aircraft, particularly during approach and landing on a runway. Current systems use instrument landing systems (ILS), microwave landing systems (MLS), or satellite landing systems, such as the Ground Based Augmentation System locating system (GLS), to safely guide aircraft during approach to a runway.
Some current display systems are designed to make landing displays more intuitive for pilots. One approach has been to display a runway symbol (i.e., a synthetic runway) which represents the position and orientation of a target runway relative to a pilot's point of view. The advantages of such a display system include reductions in pilot workload, pilot fatigue, and pilot error. Reduced workload enables a pilot to perform better during approach and landing. However, it is disadvantageous if the synthetic runway display is not properly aligned with the target runway and guidance cue during approach.
Synthetic runway vision systems rely on GPS position and airport/runway database information to render a “first person” view of topography in front of an airplane. The accuracy of these synthetic runway vision systems is limited by the accuracy of the GPS position estimate and the accuracy of the runway database information, which in turn limits the operational usefulness of the function.
Highly accurate, differentially corrected GPS data is available in certain locations via Satellite-Based Augmentation Systems (SBAS), but even then, runway database errors can result in erroneous display of a synthetic runway.
It would be beneficial if a vision (i.e., display) system were provided having the capability to overcome inaccuracies in the GPS position estimates and in the runway database.